Emulsification of coal tar pitch



Patented June 15, 1948 UNITED STATES ATENT OFFICE EMULSIFICATION OF COALTAR PITCH of Great Britain No Drawing. Application February .6, 1945,Se-

rial 1943 2 Claims.

This invention relates to the controlled preparation of aqueousemulsions of coal tar pitch.

Heretofore it has not been considered to be commercially practicable toemulsify unselected coal tar pitch having a melting point above 50 C.,and having a working fluidity only at a temperature above 100 0.,notwithstanding that such coal tar pitch has a wide field of applicationin the coating or impregnation of paper and paper board.

In seeking to emulsify coal tar pitch from different sources by theprocess described in the specification of British Patent No. 462,111, wehave occasionally obtained irregular results, due to variations in thechemical and physical properties of such pitches even when ofsubstantially the same melting point and comparable fluidity.

As the result of experimental research we have now found that theirregular results mentioned above can be largely eliminated by usingnatural asphalt, such as Trinidad asphalt, as an assistant emulsifier inthe emulsification of coal tar pitch, it may be in conjunction with aproportion of fatty acid pitch or fatty acid, and dispersing the blendin a hot dilute aqueous solution of an alkali, preferably a fixedalkali, employing as an additional assistant emulsifier a proteincompound, with or without the presence of an organic salt or salts, forexample, sodium oleate, with or without the presence of a colloidal claysuch as bentonite.

For the purpose of our invention the Trinidad asphaltmay be blended (a)with the coal tar pitch before the addition of fatty acid or fatty acidpitch, or (b) with fatty acid or fatty acid pitch before its addition tothe coal tar pitch.

Emample the alkali refining of linseed oil. When linseed oil is treatedwith hot aqueous alkali, the free fatty acids present in the linseed oilare saponi- It is a by-product of Lil No. 576,512. In Great BritainDecember 2,

2 fled and are dissolved in the aqueous medium in which the alkali wasdissolved. On standing, the aqueous and oleaginous phases resolve intolower and upper layers, respectively. The aqueous phase after beingseparated is acidified with sulfuric acid to precipitate the free fattyacids and two layers again form. The oleaginous layer is linseed acidoil, the approximate composition of which is:

Per cent Linseed-oil-free fatty acids Tcontained in the original linseedoil) Entrained linseed oil 40 Mucilage and water 10 We claim: 1. Theprocess of producing an aqueous emulsion of a coal tar pitch having amelting point above 50 C. and a working fluidity only at a temperatureabove C., which comprises blending the coal tar pitch with an assistantemulsifier comprising Trinidad asphalt and linseed acid oil, anddispersing the blend of coal tar pitch, Trinidad asphalt and linseedacid oil in a hot dilute aqueous alkaline solution.

2. The process of producing an aqueous emulsion as defined by claim 1,in which 10 parts by weight of Trinidad asphalt and 7.5 parts by weightof linseed acid oil are blended with each 100 parts by weight of coaltar pitch.

JOHN ALEXANDER MONTGOMERIE. PE'IER KENNEDY ARCHIBALD. LEONARD CHARLESBRADSHAW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,190,604 Montgomerie et al. Feb.13, 1940 1,734,437 Kirschbraum Nov. 5, 1929 1,725,648 Kirschbraum Aug.20, 1929 FOREIGN PATENTS .Number Country Date 462,111 Great Britain Mar.2, 1937 421,269 Great Britain Dec. 6, 1934 332,591 Great Britain July22, 1930 28,178 Great Britain 1910 670,870 France Aug. 26, 1929 665,060France Apr. 30, 1929 134,983 Austria Oct. 25, 1933

